RELAXATION PHENOMENA IN LITHIUM-ION-INSERTION CELLS

Relaxation phenomena in lithium-ion-insertion cells are modeled. Simul ation results are presented for a dual lithium-ion-insertion cell and for a cell using a lithium-foil negative electrode. A period of relaxa tion after a charge or discharge can cause appreciable changes in the distribution of material in the insertion electrodes. Local concentrat ion cells in the solution phase and an open-circuit potential that dep ends on state of charge f or the solid phase drive the redistribution of material. Concentration profiles in solid and solution phases durin g relaxation are analyzed, and the consequences for cell performance a re discussed. The model predicts the effects of relaxation time on mul tiple charge-discharge cycles and on peak power. Galvanostatic and pot entiostatic charging are simulated; the results are compared to experi mental data for a commercial battery.